FDA Panel Slams Endologix Response to Stent-Graft Safety Issues

November 10, 2021

The US Food and Drug Administration (FDA) has long kept a watchful eye over successive iterations of endovascular stent graphs in the Endologix AFX line, designed for repair of abdominal aortic aneurysms (AAA). For years, the devices, first approved in 2011, have drawn safety alerts and recalls , stemming from what the agency says was a "higher than expected" risk for potentially injurious or fatal type III endoleaks.

As part of the latest review process, Endologix recently showed regulators data from a rare randomized trial of the AAA endovascular aneurysm repair (EVAR) technique. The company said the recent postmarket study LEOPARD suggested the type III endoleaks — blood seeping around or through the device into the aneurysm — are no more common with the current AFX2 system than with other available AAA stent-grafts.

Technical upgrades to its AFX line of EVAR devices in recent years have largely resolved the safety issues identified in previous models, the company argued.

But the company's case was unconvincing for a majority of the FDA Circulatory System Devices Advisory Panel that assembled virtually on November 2. A number of panelists questioned the earnestness with which Endologix worked to rectify the safety alert and recall issues. Many also decried the real-world relevance of the randomized trial presented as evidence, with its follow-up time of only a few years.

The panel that included more than a dozen clinicians — mostly surgeons or interventional cardiologists or radiologists — were not instructed to formally vote on the issues. But it ultimately advised the FDA that more exacting studies with longer follow-ups appear needed to show that the device's benefits in routine use outweigh its risks, especially for type III endoleaks.

"There isn't a tremendous amount of confidence" that Endologix had enacted sufficient risk-mitigation measures in the wakes of the safety alerts and recalls, chair Richard A. Lange, MD, MBA, Foster School of Medicine and Texas Tech University Health Sciences Center, El Paso, said when summarizing the panel's take on the day's proceedings.

Although the stent-graft's safety seemed improved with recent design changes, the panel wasn't convinced the upgrades could take the credit, or even that they were aimed specifically at preventing endoleaks, Lange said. "Nobody feels assurance that the problem has been solved."

"I believe that the type-three endoleaks pose a challenge to patients, and I have not seen enough data to assure me with a degree of certainty that that problem no longer persists," said panelist Joaquin E. Cigarroa, MD, a cardiologist at Oregon Health & Science University, Portland. His take on the LEOPARD trial, moreover, is that it "does not refute that there is an issue, given the duration of follow-up."

On the other hand, a majority of the panel agreed that, currently, the AFX2's benefits would likely outweigh risks for patients in narrowly defined high-risk anatomic or clinical scenarios and those with no other endovascular or surgical option.

"I do believe that there are patient subsets where the Endologix graft can play an important and vital role," surgeon Keith B. Allen, MD, St. Luke's Mid America Heart & Vascular Institute, Kansas City, Missouri, offered from the panel.

"In patients that don't have aneurysmal disease but have distal bifurcation proximal iliac disease, it can be a very nice graft to use and solves a problem," he said. "To remove that graft completely from the market I believe would deny a subset of patients."

But for aortic aneurysms in routine practice, Allen said, "I think there are some red flags with it."

Joining the day's proceedings as a public commenter, surgeon Mark Conrad, MD, St. Elizabeth's Hospital, Boston, Massachusetts, agreed that "there's not one commercial device out there that is able to handle every anatomy."

Having options for patients is important, he said, because "the biggest problems we run into are when somebody only uses one graft, and they try to make that fit everything."

Another public commenter offered a similar take. "I think we haven't done a great job in the vascular surgery community really honing in on the detailed nuances that separate one device from another," said Naiem Nassiri, MD, Yale New Haven Hospital Heart & Vascular Center, Connecticut.

The Endologix device, he said, "serves a very specific role under certain anatomic configurations and limitations, and really, truly fills a gap" left by other available grafts. It suits a very specific niche, "and I think it needs to be explored further for that."

Endologix representatives who advise clinicians could play a better role in familiarizing operators with the EVAR system's strengths and limitations, proposed several panelists, including Minhaj S. Khaja, MD, MBA, interventional radiologist at UVA Health and the University of Virginia, Charlottesville.

"There definitely needs to be more education of the clinical reps as well as the physicians implanting these devices," he said, regarding the type III leaks, patient selection issues, appropriate imaging follow-up, "and the potential for increased reintervention."

All public commenters, Lange observed, had been invited to disclose potential conflicts of interest, but it was not mandatory and none did so during the public forum. Disclosures of potential conflicts for the panelists are available on the FDA site.

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